The best replacement for xfce4 is openbox.

The best alternatives to xfce4 are rated as following:
★★★★★  openbox
★  icewm

Your alternative for xfce4 is not listed? Suggest!
Speaking about xfce4, one probably shouldn't forget about compiz.

Other search terms related to xfce4 and their ratings are:
★★★★★ compiz
You have in mind a companion for xfce4 and it is not yet here? Propose!



Google Trends

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xfce4
openbox
icewm